我们知道为了提高代码的运行速度，我们需要对书写的python代码进行性能测试，而代码性能的高低的直接反馈是电脑运行代码所需要的时间。这里将介绍四种常用的测试代码运行速度的方法。
第一种：使用time模块对代码的运行时间进行统计，代码如下：

<code class="prism language-python has-numbering"><span class="token keyword">import time


<span class="token keyword">class <span class="token class-name">Debug<span class="token punctuation">:
    <span class="token keyword">def <span class="token function">mainProgram<span class="token punctuation">(self<span class="token punctuation">)<span class="token punctuation">:
        start_time <span class="token operator">= time<span class="token punctuation">.time<span class="token punctuation">(<span class="token punctuation">)
        <span class="token keyword">for i <span class="token keyword">in <span class="token builtin">range<span class="token punctuation">(<span class="token number">100<span class="token punctuation">)<span class="token punctuation">:
            <span class="token keyword">print<span class="token punctuation">(i<span class="token punctuation">)
        end_time <span class="token operator">= time<span class="token punctuation">.time<span class="token punctuation">(<span class="token punctuation">)
        <span class="token keyword">print<span class="token punctuation">(f<span class="token string">"the running time is: {end_time - start_time} s"<span class="token punctuation">)
        

<span class="token keyword">if __name__ <span class="token operator">== <span class="token string">"__main__"<span class="token punctuation">:
    main <span class="token operator">= Debug<span class="token punctuation">(<span class="token punctuation">)
    main<span class="token punctuation">.mainProgram<span class="token punctuation">(<span class="token punctuation">)</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></code>

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我们采用time 模块给所要测试的代码的前后加上时间戳，一个记为start_time，一个记作end_time，最后代码块的运行时间为end_time-start_time，单位为s(秒)。当然在python中还有许多的记录时间的模块，这里不做过多讨论，均类似于time模块，实现思路上一致，代码实现上大同小异。
第二种：使用IPython的Built-in magic commands,%time,代码如下：

<code class="prism language-python has-numbering"><span class="token keyword">class <span class="token class-name">Debug<span class="token punctuation">:
    <span class="token keyword">def <span class="token function">mainProgram<span class="token punctuation">(self<span class="token punctuation">)<span class="token punctuation">:
        <span class="token operator">%time <span class="token keyword">for i <span class="token keyword">in <span class="token builtin">range<span class="token punctuation">(<span class="token number">100<span class="token punctuation">)<span class="token punctuation">: <span class="token keyword">print<span class="token punctuation">(i<span class="token punctuation">)
        

main <span class="token operator">= Debug<span class="token punctuation">(<span class="token punctuation">)
main<span class="token punctuation">.mainProgram<span class="token punctuation">(<span class="token punctuation">)
<span class="token triple-quoted-string string">"""
Wall time: 1.99 ms
"""</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></code>

这个类定义是可以去掉的，并不会影响最终的结果，%time 后面加上想要计算时间的代码，然后编译器就会在运行后自动给出所测试代码的运行时间，但是经过测试，%time方法测出的时间并不准确，时间波动范围非常大，这个是很好理解的，因为计算机每时每刻都在处理一些进程，也就是说计算机的运行状态每时每刻都是不同的，所以在不同的时刻测试同一段代码的运行时间也会得到不同的结果。

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